Chandra Singh was in the Drinking Water Office when suddenly the explosives he was carrying exploded, fatally injuring him.
Singh was rushed to the Seti Zonal Hospital where he breathed his last while undergoing treatment, police said.
The incident occurred on the eve of the second round of local-level elections which is taking place in 334 local units in 35 districts of provinces number 1, 5 and 7.
Meanwhile, an improvised explosive device exploded in the house of Prem Bhandari, ward candidate of Bhojpur Municipality-4, representing Nepali Congress.
Meanwhile, a bomb disposal team of the Nepal Army defused an improvised explosive device planted near the house of Nepali Congresscandidate for the post of Mayor Tulasipur Sub-Metropolitan City in Dang district in western Nepal, Monday night.
Security has been tightened at all the polling centres and voting stations in the district.